November 3, 2026 election: California votes on a new congressional map. People who live in the current 4th District vote in 4 of the new districts:
- District 4: 53% of residents. On the ballot: Eric Jones (Democratic); Mike Thompson (Democratic).
- District 1: 27% of residents. On the ballot: Mike McGuire (Democratic); James Gallagher (Republican).
- District 8: 20% of residents. On the ballot: John Garamendi (Democratic); Rudy Recile (Republican).
- District 2: less than 0.1% of residents (390 people in the 2020 census). On the ballot: Jared Huffman (Democratic); Robin Littau (Republican).
Shares are based on 2020 census population. To confirm your own district, use the California voter lookup or enter your street address in the district lookup. The state's lookup is final. The map and ZIP codes on this page show the current 119th Congress district. See the redistricting tracker for what changed in each state.
California’s 4th Congressional District is represented by Mike Thompson (D) in the U.S. House of Representatives. The district is one of California’s seats in the 435-member House of Representatives. After the 2020 Census, the average congressional district had 761,169 people, according to the U.S. Census Bureau. California uses new district lines for the November 3, 2026 election (the map voters approved as Proposition 50), so this district’s boundaries change with that election. The redistricting tracker explains what changed.
Congressional representatives serve two-year terms and face election every even-numbered year. The next election for this seat will take place on November 3, 2026.
Population
763,128
Median Household Income
$95,443
Population and income: U.S. Census Bureau, American Community Survey 5-year estimates for 2019 to 2023, for district lines in effect on January 1, 2023.
Partisan Lean
D+31
2024 presidential margin (Trump vs Harris). Source: The Downballot.
District boundary, 119th Congress. Boundary data: U.S. Census Bureau TIGERweb. Map tiles: OpenStreetMap.
Mike Thompson and California's 4th Congressional District
Mike Thompson, a member of the Democratic Party, represents California's 4th Congressional District and has held the seat since January 3, 2023. The boundary map for the district is above and the ZIP codes it covers are listed further down this page.
Committee assignments: House Committee on Ways and Means.
The current term ends January 3, 2027. The seat is on the ballot on Tuesday, November 3, 2026. Washington office phone: 202-225-3311. Official site: mikethompson.house.gov.
Current Representative
Rep. Mike Thompson (D)
119th Congress • Democrat • Representing this district since January 3, 2023 • In the House since January 6, 1999
Mike Thompson currently represents California’s 4th Congressional District as a member of the Democratic Party in the United States House of Representatives. The representative’s district office helps constituents with federal casework, such as Social Security claims and veterans’ benefits.
2026 Election
On the ballot November 3, 2026
- Eric Jones, Democratic
- Mike Thompson, Democratic Incumbent
This list is for District 4 as drawn for the 2026 election, which has different boundaries from the district map on this page.
Source: California Secretary of State, certified list of candidates, checked September 26, 2026. Write-in candidates are not listed.
Key dates for November 3, 2026
| Register by mail | Monday, October 19 PassedApplication must be postmarked by this date. |
|---|---|
| Register online | Monday, October 19 Passed |
| Register in person | Monday, October 19 Passed |
| Same-day registration | After October 19, you can register and vote at your county elections office or a vote center through Election Day. |
| Early in-person voting | October 5 to November 2 Open nowCounty elections offices open October 5. In Voter's Choice Act counties, vote centers open October 24. In-person voting continues on Election Day. |
| Mail ballot | Every active voter is mailed a ballot. No request is needed. |
| Return a mail ballot | Postmarked by November 3 and received by November 10, or left in a drop box by 8 p.m. on November 3. |
| Election Day | Tuesday, November 3, 2026 |
Check your registration with the California voter lookup. Dates come from the California election office and were checked September 26, 2026. States can change deadlines, so confirm with your election office before you act.
Polling places in California are open 7 a.m. to 8 p.m., local time. Confirm your registration and polling place on the official federal voter page for California: vote.gov.
What is on the ballot nationally on November 3, 2026
Contact Your Representative
Washington Office
268 Cannon House Office Building
Washington, DC 20515
Phone: (202) 225-3311
Online
Committee Assignments
About This District
The district covers all of Yolo, Napa, and Lake counties and parts of Solano and Sonoma counties in California. Its largest cities are Santa Rosa (about 178,000), Vacaville (about 102,000), Napa (about 79,000), and Davis (about 67,000).
This page covers California District 4, including its current U.S. House representative, district map, ZIP codes, and 2026 election details.
Learn more about congressional districts
- What is a congressional district?
- What does a U.S. Representative do?
- What is gerrymandering?
- How congressional redistricting works
Frequently Asked Questions
Who represents California's 4th Congressional District?
Mike Thompson (D) represents California's 4th Congressional District in the U.S. House of Representatives.
What political party is Mike Thompson a member of?
Mike Thompson is a member of the Democratic Party.
How can I contact Mike Thompson?
You can reach Mike Thompson by phone at 202-225-3311 or through their official website at https://mikethompson.house.gov.
When does Mike Thompson's current term end?
Mike Thompson's current term in the U.S. House of Representatives ends on January 3, 2027.
Where is California's 4th Congressional District?
California's 4th Congressional District is located in the state of California and is one of the 435 voting congressional districts in the U.S. House of Representatives.
What district does Mike Thompson represent?
Mike Thompson has represented California's 4th Congressional District since January 3, 2023. The boundary map for the district is on this page.
Where can I see a map of Mike Thompson's district?
The boundary map for California's 4th Congressional District is on this page. It is drawn from U.S. Census Bureau TIGERweb boundary files for the 119th Congress.
What committees is Mike Thompson on?
Mike Thompson sits on House Committee on Ways and Means. Committee assignments come from the Clerk of the House MemberData file.
Is Mike Thompson still in Congress?
This site shows Mike Thompson holding California's 4th Congressional District, checked against the Clerk of the House member list. All 435 House seats are on the ballot on November 3, 2026, so the answer can change with that election.
Nearby Districts in California
ZIP Codes in California's 4th Congressional District
This congressional district contains 74 ZIP codes. The most common 10 are shown below; expand the full list to see every ZIP in the district.
39 of these ZIP codes also extend into another California district, so a ZIP code here does not always identify a single representative. Examples include 94503 (also in the 8th), 94512 (also in the 8th), 94515 (also in the 2nd), 94533 (also in the 8th), 94534 (also in the 8th), 94535 (also in the 8th), 94571 (also in the 7th and 8th), 94574 (also in the 2nd).
- 94503
- 94508
- 94512
- 94515
- 94533
- 94534
- 94535
- 94558
- 94559
- 94562
View all 74 ZIP codes in this district
- 94503
- 94508
- 94512
- 94515
- 94533
- 94534
- 94535
- 94558
- 94559
- 94562
- 94567
- 94571
- 94573
- 94574
- 94576
- 94585
- 94591
- 94599
- 94928
- 94931
- 94951
- 94952
- 94954
- 95401
- 95403
- 95404
- 95405
- 95407
- 95409
- 95422
- 95423
- 95426
- 95431
- 95435
- 95439
- 95442
- 95443
- 95451
- 95452
- 95453
- 95457
- 95458
- 95461
- 95464
- 95467
- 95469
- 95472
- 95476
- 95485
- 95492
- 95493
- 95605
- 95606
- 95607
- 95612
- 95616
- 95618
- 95620
- 95625
- 95627
- 95637
- 95645
- 95653
- 95679
- 95687
- 95688
- 95690
- 95691
- 95694
- 95695
- 95697
- 95698
- 95776
- 95937
ZIP-to-district boundaries sourced from the U.S. Census Bureau's 2024-07-30 Block Equivalency File for the 119th Congress. ZCTAs (ZIP Code Tabulation Areas) approximate USPS delivery ZIPs.
U.S. Senators for this state: Adam B. Schiff (D), Alex Padilla (D)
Local surveillance camera contracts
Automated license plate reader contracts are approved locally, by city councils and county boards, not by Congress. These places in this district have a contract record documented from public sources:
Records compiled by Who Approved This, an independent public-records project. Approval dates, amounts, and end dates are cited to council agendas, minutes, and signed contracts.
Place list rebuilt from the Who Approved This public export on September 26, 2026.
Last updated September 27, 2026.
Data last checked September 26, 2026.
See how this district compares with another using Compare Districts.